@Entity public class Employee { @Id @GeneratedValue private long id; @Index private String name; // other fields and methods } @Entity @IdClass(EmployeeId.class) public class Employee { @Id @GeneratedValue private long id; @Id @Index private String department; // other fields and methods } @Entity public class Employee { @Id @GeneratedValue private long id; @Index(unique=true) private String email; // other fields and methods }